Drowning is a process involving respiratory impairment due to submersion or immersion in a liquid. This can occur when a person’s airway is below the surface of the liquid (submersion) or when liquid splashes across the face, preventing breathing (immersion). Drowning centers on the body’s inability to take in oxygen, leading to a cascade of physiological responses and potential harm.
The Body’s Immediate Response
Upon submersion, especially in cold water, the body exhibits immediate, involuntary reactions. The gasp reflex, an uncontrollable inhalation, can lead to water entering the airways. Simultaneously, individuals instinctively attempt to hold their breath, a voluntary action that soon becomes involuntary as the urge to breathe intensifies.
The “cold shock response,” triggered by cold water, can cause rapid breathing and reduced breath-holding time, further increasing the risk of water inhalation. Another reflex, the mammalian diving reflex, particularly pronounced in cold water and in children, involves slowed heart rate (bradycardia) and constriction of blood vessels to redirect oxygenated blood to the brain and heart. Despite these protective mechanisms, the struggle for oxygen quickly become overwhelming.
Water Entry and Lung Effects
When water enters the airways, it can trigger a protective reflex called laryngospasm, where the vocal cords clamp shut. This reflex prevents water from entering the lungs, but also blocks air intake, leading to oxygen deprivation. In some instances, this spasm may persist, meaning no water enters the lungs, a phenomenon historically referred to as “dry drowning.” However, in most drowning cases, the laryngospasm eventually relaxes, and water is aspirated into the lungs, commonly termed “wet drowning.”
Once water enters the lungs, it harms the delicate structures responsible for gas exchange. The water washes away pulmonary surfactant, a substance lining the alveoli (air sacs) that prevents their collapse. Without sufficient surfactant, the alveoli collapse, impairing the lungs’ ability to absorb oxygen and expel carbon dioxide. This leads to fluid accumulation in the lungs, known as pulmonary edema, and can result in acute respiratory distress syndrome (ARDS), making breathing extremely difficult.
Systemic Impact of Oxygen Deprivation
Oxygen deprivation, or hypoxia, rapidly affects the entire body, with the brain being the most sensitive organ. Brain cells experience irreversible damage within approximately four to six minutes of oxygen deprivation. This can lead to loss of consciousness, memory impairment, and motor coordination difficulties.
As oxygen levels fall, other vital organs also suffer. The heart may develop irregular rhythms (arrhythmias) and cease functioning, leading to cardiac arrest. Kidneys can also be affected, with acute kidney injury being a common complication. The severity of damage to these systems is directly related to the duration of oxygen deprivation.
Post-Rescue Complications
Even after rescue from a drowning incident, medical complications can arise. Some individuals may experience “secondary” or “delayed drowning,” where pulmonary issues develop hours after the event. These delayed symptoms, such as persistent coughing, labored breathing, or chest pain, indicate ongoing fluid accumulation and inflammation.
Medical intervention following rescue often includes cardiopulmonary resuscitation (CPR) and mechanical ventilation to restore breathing and oxygenation. Despite successful rescue, the brain’s vulnerability to oxygen deprivation means long-term neurological damage is a significant concern. Survivors may face lasting cognitive difficulties, including memory, attention, and problem-solving issues, which can manifest years later.